JPS59195306A - Recording and reproducing device of pcm signal - Google Patents

Abstract

PURPOSE:To attain both read-after-write and write-after-read functions with a single head by giving >=3 revolutions to a rotary head in a stop or extremely slow forward state of a tape and allotting either one of erasion, record and reproduction modes to the tape contact period of the head for each of said three revolutions. CONSTITUTION:A tape is wound obliquely around a guide drum in an angle range so as to produce a period during which a rotary head has no contact with the tape at all for each revolution of the head. Then a rotary head 1 is revolved by 90rpm, for example, equal to three times as the number of revolutions NS of a standard rotary head. Then 1/30sec, i.e. a period of three revolutions is defined as one cycle. For the right-after-read operation, the head 1 switches its operation mode every reolution to perform erasion in a period RT1 of the 1st revolution, record in a period RT2 of the 2nd revolution and reproduction in a period RT3 of the 3rd revolution during a cycle of three rotations respectively. A tape 2 is kept at pause during a period up to a 90 deg. rotary phase at the beginning of the period RT3. Therefore the head 1 scans three times the same position on the tape 2 and performs the erasion, record and reproduction respectively for each scan.

Description

[Detailed Description of the Invention] Industrial Application Field This invention is applicable to information signals such as audio signals and video signals.
The present invention relates to a device for recording and reproducing CM signals using a rotating head.

BACKGROUND TECHNOLOGY AND PROBLEMS High-quality recording and playback can be achieved by converting information signals such as audio signals into PCM. There are two methods for recording and reproducing PCM signals: a fixed head method and a rotating head method. The rotating head method has the advantage that the relative speed of the head is high and high-density recording is possible relatively easily.

Incidentally, one of the important functions in a tape recorder is a read-after-write or write-after-read function. An example of the read-after-write function is, in the case of an audio tape recorder, a so-called follow-up recording function that superimposes another audio signal on the reproduced sound and re-records it while the audio is being played back. An example of the write-after-read function is a recording monitor function that plays back recorded signals while recording.

Conventionally, in order to realize these functions, three heads have been installed in the order of the erasing head, the recording head, and the playback head in the scanning direction of the head, regardless of whether it is a fixed head method or a rotating head method. Must be.

Especially in the case of a rotating head system, when considering the case where the head drum is flush with a small size in order to downsize the device,
Arranging three heads in this way would be unreasonable in terms of space. This is a record.

This is especially noticeable when using several playback heads at night.

Purpose of the Invention The present invention uses a rotating head system as a PCM signal recording and reproducing device, and can realize read-after-write and write-after-read functions with one head, instead of three heads as in the conventional case. The purpose is to provide equipment.

SUMMARY OF THE INVENTION The present invention utilizes the features of a rotary head type recording/reproducing machine.

In other words, in the case of the rotating head method, unlike the fixed head method, which forms tracks continuously in the longitudinal direction of the tape, diagonal tracks are formed at a constant pitch in the width direction of the tape. Since the tracks are inherently discontinuous, it is easy to time-compress and record the PCM signal.

Furthermore, in the rotary head system, the head can be moved even when the tape is stopped, so recording and reproduction can be performed even when the tape is stopped.

Utilizing the above features, the present invention is configured as follows. That is, the present invention obliquely wraps the tape around the guide drum over an angular range such that the rotary head completely wraps around the tape during one revolution of the rotary head, so that the tape contacts the rotary head. The PCM signal, which has been time-compressed for the tape contact period, is recorded and reproduced during the tape contact period, and this recording and reproduction is performed while the tape is in a stopped state or in an extremely low-speed transport state close to a stopped state. The rotary head is rotated three times or more while the tape is stopped or is being fed at a very low speed, and the head is in contact with the tape during each of the three rotations during one of three operations: erasing, recording, and reproducing. As a result, one head performs the above read-after-write or write-after-read function.

Then, during the period during which the head does not come into contact with the tape after the period of three or more rotations has elapsed, the tape is moved by one pitch of the track to be scanned by the rotating head. In other words, the tape is transported by intermittent tape feeding.

Embodiment Hereinafter, one embodiment of the present invention apparatus will be described.
Let's explain the case of recording and reproducing in M format with reference to the diagram as an example.

In this example, as shown in FIG. 1, one rotary head (1) is used, and the tape (2) is wound around the drum (3) at an angle of 90°.

First, write-after-read, or recording while monitoring, will be explained.

Normally, when recording with a rotating head, one rotation is one rotation.
Normally, records are made as cycles, but in this example, 3
Records are made with each rotation as one cycle.

In this case, the rotation speed of the rotary head can be arbitrarily determined, but in this example, the following points are taken into consideration.

Now, for example, using a rotating head device as shown in Fig. 1,
As a general recording method for recording M signals, the head (1) is rotated at a rotational speed NS1, for example, 3Q rps, the tape (2) is transported at a constant speed, and the PCM audio signal is transferred to the head (1). for the tape contact period, i.e., 90°/360°---! - A possible method is to compress the time and record with the head (11), with one rotation as one period.If a device using this recording method is considered a standard device, in this example, the signal processing system of this standard device Consideration has been given to ensuring compatibility.

In other words, in the case of this standard device, the audio PCM signal for one rotation, or 1.1 m seconds, is time-compressed and recorded as one track. Seconds of order 0 Io PCM signals are recorded as one track.

Therefore, in this example, the rotary head (1) is rotated at three times the rotation speed NS of the rotary head of this standard device, for example, 9 Qrps, and the period of 3 rotations, 100 seconds, is defined as one cycle (see Figure 4A). ).

If the rotational phase of the rotary head (1) at which the rotary head (1) just begins to contact the tape (1) is 08, and one rotation begins from this point, then in Fig. 4B @a
As shown with , during the 90° rotation angle period at the beginning of each rotation of one cycle of three rotations, the head (1)
) and scan diagonally.

Then, the period RT1 of the first rotation of this one cycle three simultaneous rotation periods
The tape (2) is stopped during the period from the rotational phase of θ° to the rotational phase of 90° during the third rotation period RT s, and the tape (2) is stopped at the rotational phase of 90° during the third rotation period RT3. A DC voltage DR as shown in FIG. 4C is supplied to the capstan motor between the time when (1) stops coming into contact with the tape (2) and the start of the next cycle.
This motor is driven, and the tape (2) is thereby transported at a relatively high speed by one track pitch during this period. In this case, the tape (2) is transferred by one track pitch from 900 to 360'(0') in terms of the rotational phase of period RT3, and then at the point of rotational phase of 0° in period RT1 of the next cycle. Now, all you have to do is make sure it is stopped, and this o
It is not necessary to match the tape stop time to the rotation phase of o.

The change in speed of tape (2) is shown in the fourth diagram.

A step motor can be used as the capstan motor.

FIG. 2 shows a block diagram of an example of the device of this invention.
) is the rotating head drive motor, (7) is the rotating head (1)
This is a pulse generator that generates a pulse PQ indicating a rotational phase of
(z) is supplied to the drum phase servo circuit C30+, and the reference 9QH is supplied from the control signal generation circuit section.
The signal SR of z is supplied to this drum phase servo circuit (3o), and the motor (6) is controlled by the output of this servo circuit (■), so that the rotary head (1) rotates in a constant phase relationship with respect to the reference signal SR. controlled as follows.

In addition, (8) is a pinch roller, (9) is a capstan, and the capstan drive motor (101 is the aforementioned capstan interlocking voltage DR (101) from the control signal generation circuit section.
FIG. 4C) is supplied and tape pages 2) are intermittently transferred as described above.

Then, the rotating head (11
is erased in the first rotation period RTI of one cycle of three rotations, recorded in the second rotation period RT2, and reproduced in the third rotation period RT3. The mode is switched every rotation so that

As mentioned above, since the tape (1) is stopped during the period up to the 90° rotation phase at the beginning of the third rotation period RTa, the rotating head (1) rotates the same position on the tape (1) three times. It scans twice, and performs erasing, recording, and reproducing operations during each scan.

(t9) is a switch circuit for switching the mode of this rotary head (1), which is switched to the terminal P side during the period RTI, to the terminal P side during the period RT2, and to the terminal P side during the period RTs according to the switching signal SW from the control signal generation circuit section. On the terminal P side,
Each can be switched.

Therefore, during period RTI, the erasing signal generating circuit α8)
Since the erasing signal from RT is supplied to the rotary head (1) via this switch circuit (IEII),
] During the tape contact period ER, the rotating head fil
Erasing operation is performed by VC.

Next, in period RT2, the time-compressed audio PCM is recorded in the tape contact period as follows.
The signal is recorded.

The audio signal through the input terminal (111) is supplied to the A/D converter circle, for example at a sampling frequency of 44.
The sampled signal is sampled at 1 kHz, and the sampled signal is a PCM signal with, for example, 16 pits per sample.
converted into a signal. The output DS of this A/D converter 112) is supplied to a recording encoder 03). This recording encoder (I3) has two memory circuits such as RA.
M(14) α9 is connected to a parity word and CRC code addition circuit [6]. In this recording encoder (13), one period of three rotations Dn+t,
For every Dn+2 - (n is an integer), two I(, AMC
I4) σ5) is written as shown in FIG. 4F and G.

At this time, as will be described later, the reproduction signal of the PCM signal two cycles before is read out simultaneously with the aging. As is well known, this simultaneous writing and reading can be accomplished by dividing one memory access period into a reading period and a reading period, and performing the writing and reading in a time-sharing manner.

Thus, for each cycle period, RAM (141(151
The PCM signals alternately written in the head (1
) is not in contact with the tape (2), a parity and CRC code generation addition circuit adds a parity word for error correction and a CRC code for error detection, and the original R・AM (14) (15 ) becomes obsolete.

J' with this parity word and CRC code added
The CM data is read from each RAMQ4) and (151) at a speed approximately 12 times faster than the writing speed during the tape contact period R and EC, which is the initial 90' phase angle period of 1゛2, between the second rotation of the button. At this time, since the switch circuit (11) is switched to the terminal P side, this read PCM signal is sent to the amplifier at> and the switch circuit a9.
The recording material is supplied to a rotating head (1) through the tape (2) and recorded as one diagonal track (4) on the tape (2) as shown in FIG.

In addition, the recording encoder (t3) processes data by dividing it into blocks of multiple samples and adding block synchronization signals and address signals to these blocks, interleaving processing to strengthen against burst errors, and further processing to make signals suitable for recording and playback. Processing such as modulation is also performed.

During the third rotation period RTa, the switch circuit α9 is switched to the terminal P side and the playback mode is entered, so that during the tape contact period FB, which is the rotational phase angle period of 90° at the beginning of this period RT3, the head ( 1), the previous period R
A PCM signal is extracted from the track recorded at T2, and this reproduced signal is sent to a switch circuit (19) and an amplifier (21).
) is supplied to the digital signal restoration circuit (2) to restore the digital PCM signal, which is then supplied to the decoder to restore the tape contact period 1 (2) of the previous period (2) and the RAM (2) from which data was only read by the EC. 14) or (15)
will be written to. De-interleaving processing is performed during this writing.

The playback data written to this RAMg4) or (151) is transferred to the head (1) on the tape (2) of 1゛3 during this period.
During the remaining period in which no contact occurs, error correction is performed by the correction circuit (24) using the C)LC code and parity word.

During the period in which the head (1) does not come into contact with the tape (2), the tape (2) is moved by one track as described above.

During the next cycle, the error-corrected reproduced PCM data is read out from the RAM (14) or at the write speed of ■, and this data is read out from the RAM (14) or a-side at the writing speed, and this is read out from the error correction circuit 25+.
After the data that could not be corrected is corrected, it is supplied to the D/A converter (c) and returned to the original analog audio signal, and this analog audio signal is sent to the output terminal through the amplifier (2η). is derived.

Then, when reading this reproduced PCM data, this 1
Data DS from the A/D converter circle for a period of time is written to the same RAM. Thereafter, the above operations are repeated.

Therefore, a monitor signal is obtained at the output terminal (281) in a state delayed by two cycles with respect to the recording data DS, as shown in FIG. 4H.

As described above, the write-after-read function, that is, the recording monitor function, can be realized with only one rotary head.

Next, let us explain the read-after-write function, for example, when it performs a follow-up recording function.

FIG. 5 is a diagram showing a time chart in this case. In this case as well, as shown in FIG. 5A, there are three simultaneous rotations in one cycle, and the head (1) rotates at three times the speed of the standard device.

During the third rotation of the three rotations in one cycle, during which the head (1) of RTa does not contact the tape (2), the driving voltage DR of the capstan motor (II) is increased as shown in FIG. The tape (2) is fed and transported by one track pitch in exactly the same way as in the previous example.Therefore, as shown in the figure, during the first rotation period R'l'l,
The tape (2) stops during the contact period corresponding to 90' rotation angle at the beginning of the second rotation period RT2 and the third rotation period RT3, as shown in FIG. In each period, the head (1) repeatedly scans the same track position on the tape (2) three times.

However, when performing this follow-up recording function, the first rotation period RTI of the three concave rotations in one cycle is played, the second rotation period RT2 is erased, and the third rotation period RT3 is recorded. The switch circuit α9) is switched as follows.

Then, as shown in FIG. 5B, the first rotation period RT z
Then, during the tape contact period, the head (1) scans the track on which the PCM signal was previously recorded, and the reproduced signals Dn, Dn+I, Dn+2, - are taken out, and this is done in the same way as described above. It is written to the RAM (14) in every other cycle period, and to the RAM (15) in the remaining every other cycle period (see FIGS. 5E and F). The playback data written to this RAM Q4) or a9 is stored in the remaining head (1
The correction circuit (
24), error correction is performed. Then, this error-corrected reproduced data is expanded to the original time axis and read out during three rotations from the second rotation period R1゛2 to the first rotation period RTt of the next one cycle period. (5th
(see Figure G) and converted back to an analog audio signal. At the same time, this reproduced analog audio signal
The signal to which the signal you want to superimpose is added is the input terminal (1)
) is supplied to the A/D converter (12) through P
This PCM signal Dn-x +DA is converted into a CM signal.
, Dn + DB.

Dn+x+DC... are simultaneously written to the same RAM (see FIG. 5H).

Next, when it comes to period unit 2 of the second rotation, this period RT
During the tape contact period of the head (1), which is the first rotation angle period of 90°, an erasing signal from the erasing signal generation circuit is supplied to the rotating head (1), erasing the previous recorded signal. be done.

And during this period, the tape (2) of RTz was hit 1)
In the period in which there is no contact, R for the 18th period before that
, AM (141 or PCM data D omitted in αω
n-+ +DA, Dn 10DB, Dn-+-1+
In the recording encoder (13), a parity word and a CRC code are generated and added to the DC.

At the next third rotation period 1 (T3), during the first tape contact period, the PCM signals Dn-t +DA, Dn to which the parity and CRC codes are added are
+DB, Dn+x +DC, . . . are read out, supplied to the rotary head (1) via an amplifier (In), and recorded as one track (4) on the tape (2).

Then, during the period after this period RT3 when the head (1) does not come into contact with the tape (2), the tape (2) is
It is transferred by the track pitch.

As described above, very good follow-up recording can be performed.

In this case, the signal reproduced during the contact period of the first rotation period RT1 of one cycle period is returned to the original time axis and output terminal C2
8I, and a new signal to be added is added to this reproduced signal and time-compressed again.
It is recorded in the contact period RT20 during the second rotation of the next one cycle period. In other words, follow-up recording is performed with a one-track shift.

Here, during reproduction, tracking control is required to ensure that the rotary head correctly scans the recording track, and various methods can be used for this. For example, a pilot signal for tracking is recorded by superimposing it on the recording signal in a state where it can be separated in frequency from the recording signal, and this pilot signal is extracted from the playback output of the rotary head, and the tracking position is determined by the output of this pilot signal. There are methods available to control this.

In the above example, one period is a period of three rotations, but since the present invention requires at least one period of three concave rotations, one period can be made to be three or more rotations.

Further, although the above example has been explained with reference to a case where there is one rotary head, the present invention can also be applied to a case where there is a plurality of rotary heads. For example, if there are two rotating heads,
For example, two heads are installed at approximately the same angular position and shifted by one track pitch in the direction of the rotation axis, and 1
When these two heads form adjacent tracks on the tape during rotation, read-after-write and write-after-read can be performed in exactly the same manner as described above. In this case, the tape is fed by one track pitch of the track to be scanned by each rotary head, that is, by two track pitches.

In addition, even if two rotating heads are not shifted in the direction of the rotation axis, every other cycle period is used as the assigned period for one rotating head, and the remaining every other cycle period is assigned as the assigned period for the other rotating head. It may be done as follows. In this case, the tape may be transferred by one track pitch.

Note that in the case of high-density recording without forming guard bands between recording tracks, the extending directions in the width direction of the gaps of the two rotary heads may be made to be different from each other.

In addition, in order to be compatible with recording/playback machines that feed the tape at a constant speed rather than intermittently, it is necessary to
) may be made to match the inclination angle when the transport is carried out at the above-mentioned constant speed.

As mentioned above, the reason why the rotary head in the above example is rotated at three times the rotation speed of the standard device is to enable it to process signals for the same amount of time as the standard device, and is a feature of this invention. It's not a requirement.

However, when considering compatibility with the standard device as well as the above-mentioned inclination angle of the recording track, it is possible to record signals recorded by the device of this invention by rotating the rotary head at 3 Qrps and feeding the tape at a constant speed. Best of all, it can be played correctly without modifying the hardware. .

Note that the tape may be fed at an extremely low speed that is considered to be almost stopped without stopping completely. In particular, since the track width for high-density recording is narrower than the scanning width of the rotary head, it is not necessary to completely stop the tape.

Effects of the Invention As described above, in this invention, a rotary head type is used as a PCM signal recording and reproducing device, and because of the features of this rotary head type and the fact that the recorded signal is a digital PCM signal, it is possible to compress the time axis of the recorded signal. Taking advantage of the ease of
A single rotating head can perform write-after-read and read-after-write functions.

Therefore, since there is no need to separately provide a dedicated rotary head for erasing, reproducing, and recording, the cost is reduced, and the diameter of the guide drum to which the rotary head is attached can be reduced.

Furthermore, by adjusting the rotational speed of the rotary head and the inclination angle of the recording track, there is an advantage that compatibility with devices using a general Tx rotary head can be easily achieved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a rotary head device used in the device of the present invention, FIG. 2 is a system diagram of an example of the device of the invention, FIG. 3 is a diagram showing an example of the recording track pattern, and FIG.
5 and 5 are time charts for explaining the present invention. (1) is a rotating spatula), (2) is a tape, (3) is a guide drum, (4) [Recording] 5 Tsuk, Q21 HaA/
D converter 1, (19) is a switch circuit for switching the mode of the rotary head, and (26) is a D/A converter.

Claims (1)

[Claims] A tape is wound diagonally around the guide drum over an angular range such that there is a period during which the rotary head does not contact the tape at all during rotation of the rotary head, and the time is compressed to the period during which the rotary head is in contact with the tape. A device in which a PCM signal is recorded and reproduced during the tape contact period, where one period is defined as n rotation periods of three or more rotations of the rotary head, and three tape contact periods of the head within one cycle. During the period including, the tape is almost stopped, and during this period, the rotary head records, reproduces, and erases the PCM signal using the three tape contact periods, and the remaining period within the one period is The tape is transported at high speed by the rotary head by one track pitch of the track to be scanned.
) CM signal recording and reproducing device.